If I bought the filter I wouldn't leave the door open. And how loud are the fans usually when they come on? And btw do you think the ducting could be stuffed in that little space in the pic I attached? Btw in case no one can visualize it this is a ROOM under the STAIRS that leads to the basement. It's a freggin closet. There is no available windows and anything leading out the room would be automatic suspicion. I can't do anything other than what I have suggested and I need to know if it will work.